PR preview environments
Preview apps are a project setting, not a hidden default on every web app. Open Project Settings → General → Preview environments. PR apps are named pr-<number>-<source-app> and get their own *.stackblaze.app host.
Step by step
Enable previews on the project
Choose Off, Auto — clone every matching app, or pin a single source app. Set Preview data to Empty (fresh datastores) or Snapshot (clone the source app’s live data). Click Save preview source.
Open a pull request
The connected GitHub repo sends a pull_request event. StackBlaze creates preview apps from the source you chose. They set STACKBLAZE_PREVIEW=true plus PR number, branch, and source name.
Use the preview URL, then close the PR
Open the preview app from the phase canvas or Deployments. Closing or merging the PR removes the preview apps. This is not a separate preview.stackblaze.cloud hostname scheme.
What we do not do
There is no per-app Preview tab. Optional Seed SQL path (for example .kubero/preview-seed.sql) is passed to the preview app as STACKBLAZE_PREVIEW_SEED_PATH — StackBlaze does not run that file as a platform job.